Dart-N-Flutter

# Dart and Flutter

Best practices recommended by the Dart and Flutter teams. These instructions were taken from [Effective Dart](https://dart.dev/effective-dart) and [Architecture Recommendations](https://docs.flutter.dev/app-architecture/recommendations).

Effective Dart

Over the past several years, we've written a ton of Dart code and learned a lot about what works well and what doesn't. We're sharing this with you so you can write consistent, robust, fast code too. There are two overarching themes:

1. **Be consistent.** When it comes to things like formatting, and casing, arguments about which is better are subjective and impossible to resolve. What we do know is that being *consistent* is objectively helpful.

If two pieces of code look different it should be because they *are* different in some meaningful way. When a bit of code stands out and catches your eye, it should do so for a useful reason.

2. **Be brief.** Dart was designed to be familiar, so it inherits many of the same statements and expressions as C, Java, JavaScript and other languages. But we created Dart because there is a lot of room to improve on what those languages offer. We added a bunch of features, from string interpolation to initializing formals, to help you express your intent more simply and easily.

If there are multiple ways to say something, you should generally pick the most concise one. This is not to say you should `code golf` yourself into cramming a whole program into a single line. The goal is code that is *economical*, not *dense*.

The topics

We split the guidelines into a few separate topics for easy digestion:

* **Style** – This defines the rules for laying out and organizing code, or at least the parts that `dart format` doesn't handle for you. The style topic also specifies how identifiers are formatted: `camelCase`, `using_underscores`, etc.

* **Documentation** – This tells you everything you need to know about what goes inside comments. Both doc comments and regular, run-of-the-mill code comments.

* **Usage** – This teaches you how to make the best use of language features to implement behavior. If it's in a statement or expression, it's covered here.

* **Design** – This is the softest topic, but the one with the widest scope. It covers what we've learned about designing consistent, usable APIs for libraries. If it's in a type signature or declaration, this goes over it.

How to read the topics

Each topic is broken into a few sections. Sections contain a list of guidelines. Each guideline starts with one of these words:

* **DO** guidelines describe practices that should always be followed. There will almost never be a valid reason to stray from them.

* **DON'T** guidelines are the converse: things that are almost never a good idea. Hopefully, we don't have as many of these as other languages do because we have less historical baggage.

* **PREFER** guidelines are practices that you *should* follow. However, there may be circumstances where it makes sense to do otherwise. Just make sure you understand the full implications of ignoring the guideline when you do.

* **AVOID** guidelines are the dual to "prefer": stuff you shouldn't do but where there may be good reasons to on rare occasions.

* **CONSIDER** guidelines are practices that you might or might not want to follow, depending on circumstances, precedents, and your own preference.

Some guidelines describe an **exception** where the rule does *not* apply. When listed, the exceptions may not be exhaustive—you might still need to use your judgement on other cases.

This sounds like the police are going to beat down your door if you don't have your laces tied correctly. Things aren't that bad. Most of the guidelines here are common sense and we're all reasonable people. The goal, as always, is nice, readable and maintainable code.

Rules

#### Style

##### Identifiers

* DO name types using `UpperCamelCase`.

* DO name ex